HELLO, DIMON PEOPLE!!!
PRICE-50-300RUR
PRICE-50R
[
PRICE-50R
10 tube of super glue
12 laser printer
chip LM2621
R2 150kOhm
R3 150kOhm
R4 500 Ohm
C2 100uF 6.3V any
So, everything is there??? LET'S GET STARTED 
HERE IS THE DIAGRAM FOR ASSEMBLY 
(I can send you a drawing via PM) 
100% LOSS OF VISION! 
Sincerely, T3012, aka KILOVOLT.
DimonVideo DimonVideo
29
liked it Today, I will tell YOU how to make a powerful laser pointer at home. To do this, we need 17 things: [ chip LM2621 16-type multimeter DT890G, allowing you to measure capacitance, resistance, voltage and so on. So, everything is there??? LET'S GET STARTED Warming up the EMPTY collimator with a soldering iron, disconnect it from the board with the button. Now, let’s put all the little things in a safe box, and we’ll make a heat sink for the Laser.
1- faulty (dead) DVD drive, speed 16-22X (the higher the speed, the more powerful the laser in it)
PRICE-50-300RUR
2- cheap chinese lantern(for 3 batteries)
PRICE-50R
3- cheap laser pointer "double-barrel" (laser pointer+ led flashlight)
PRICE-50R
4- soldering iron, power 40W (W), voltage 220V (V) with a thin tip.
5- low-melting solder (type POS60-POS61), pine rosin.
6-piece of one-sided fiberglass with dimensions 35X10mm
7- ferric chloride (sold in radio stores) price - 80-100 RUR
8-tool (tweezers, magnifying glass, small screwdrivers, pliers, long-nose pliers, etc.)
9- these are the terminal petals
(sold in any electrical store) cost from 10-35R
10 tube of super glue
11-alcohol (can be found at the pharmacy)
12 laser printer
13-page of any glossy magazine (necessarily glossy, smooth. You can also use photo paper)
14-electric iron (we take it at home. From mother, sister, grandmother, wife, they don’t see it yet)
15- radio components (you can grab some from the dead drive itself, in particular the Schottky diode, resistors, capacitors)
list of parts and their rating (ALL PARTS are SMD, i.e. for surface mounting (saving space))
R1 needs to be selected... the current on the Laser diode depends on it. I have 78kOhm current 250-300mA NO MORE!!! otherwise it will burn!!!
R2 150kOhm
R3 150kOhm
R4 500 Ohm
C1 0.1uF ceramics, for example k10-17
C2 100uF 6.3V any
C3 33uF 6.3V, preferably tantalum.
C4 33pF ceramics, for example k10-17
C5 0.1uF ceramics, for example k10-17
VD1 any 3-amp. For example
1N5821, 30BQ060, 31DQ10, MBRS340T3, SB360, SK34A, SR360
L1 in the photo you can see what it looks like... and so, 15 turns on a suitable ferrite ring or frame. You can disassemble either a computer power supply unit, an energy-saving light bulb, or a mobile phone charger, including a car mobile phone charger.
All this is not so important, the microcircuit will set everything up as it should.
17- and of course straight HANDS and “friendship with a soldering iron” or a friend who is friends with a soldering iron
We take the keychain pointer and disassemble it (CAREFULLY, DO NOT DAMAGE THE INSIDE, we will need them)
we take out the batteries, and using pliers, gently rocking them to the sides, pull out the front plastic head (where the flashlight and laser are)
Next, through the side where this plug was, we take out the insides, pushing them with a pencil from the side of the battery compartment
Then, very carefully, using a small tool with a flat tip, unscrew the plastic nut in the collimator (the brass tube where the lens and the frameless laser itself are located). We take out the contents (the plastic nut itself, the lens, the spring)
We disassemble the drive and take out the laser device carriage
EXTREMELY carefully remove the LASER, having previously wrapped the legs of the Laser with wire to prevent static.
this is the Laser Diode itself.
We take a Chinese lantern and disassemble it. Roughly similar to a flashlight pointer.
We take previously purchased terminals
and saw off them piece by piece, so that we get a type of washer, a length equal to the length of the collimator, and so that they (the washers fit tightly into each other, including the collimator itself) If they do not fit into each other, we drill them out with drills with a diameter of 5, 5-12mm for different washers, or boring.
It should look something like this:
We push the collimator itself a little further, about 5mm, this is important for fixing the Laser Diode.
Yes, we fix the washers themselves with super glue.
So, now we mount the Laser Diode by first inserting a 5mm drill into the collimator and pressing the collimator with pliers on the side of the slots where the board was.
Solder 2 wires to the LD legs. ATTENTION SOKOLEVKU L.D. We call the device with a multimeter type DT890G (it sounds like a regular diode.)
Next we need to assemble the driver circuit.
HERE IS THE DIAGRAM FOR ASSEMBLY
HERE is an approximate drawing of the conductors on the board
(I can send you a drawing via PM)
We transfer the board drawing onto glossy paper using a laser printer (laser-iron method, read on the Internet)
We make a board and solder parts onto it. It should look like this:
Assembly method, your imagination. I assembled the driver in the battery compartment, in place of the third battery.
used VARTA 800mA/H batteries
I used the lens from a flashlight pointer, but you can also use the original one from the drive
only its focal length is shorter, you will have to install another spring to prop the lens closer to the Laser Diode.
Attention! LASER RADIATION IS EXTREMELY DANGEROUS TO THE EYES!
NEVER TURN AWAY PEOPLE OR ANIMALS!
100% LOSS OF VISION!
This is the device I got:
DO NOT turn on the LD itself without a radiator, it gets very hot and will burn out. Set the current consumption of the Laser Diode to 250-300mA using resistor R1 (it is advisable to temporarily install a 100k resistor, and instead of the Laser Diode (so as not to burn the LD), a chain of 4 KD105 diodes connected in series)
Sincerely, T3012, aka KILOVOLT. ">
Turn your MiniMag laser pointer into a cutting laser with a DVD burner emitter! This 245mW laser is very powerful and is the perfect size for the MiniMag! Watch the attached video. PLEASE NOTE: you can't do this yourself WITH ALL CDRW-DVD cutter diodes!
Warning: CAUTION! As you know, lasers can be dangerous. Never point the pointer at a living creature! This is not a toy and cannot be treated like a regular laser pointer. In other words, don't use it for presentations or playing with animals, and don't let children play with it. This device should be in the hands of a reasonable person who understands and is responsible for the potential hazards posed by the pointer.
Step 1 - What you will need...
You will need the following:
1. 16X DVD cutter. I used an LG drive.
step 2 - And...
2. The MiniMag laser pointer can be purchased at any store selling hardware, sports or household goods.
3. AixiZ case with AixiZ for $4.5
4. Small screwdrivers (hourly), a utility knife, metal scissors, a drill, a round file and other small tools.
Step 3 - Remove the laser diode from the DVD drive
Remove the screws from the DVD drive and remove the cover. Below it you will find the laser carriage drive assembly.
Step 4 - Take out the laser diode...
Although DVD drives are different, each has two guides along which the laser carriage moves. Remove the screws, release the guides and remove the carriage. Disconnect the connectors and ribbon cables.
Step 5 - Continue to disassemble...
Having removed the carriage from the drive, begin disassembling the device by unscrewing the screws. There will be a lot of small screws, so be patient. Disconnect the cables from the carriage. There may be two diodes, one for reading the disc (infrared diode) and the actual red diode, which is used for burning. You need a second one. Attached to the red diode using three screws printed circuit board. Use a soldering iron to CAREFULLY remove the 3 screws. You can test the diode using two AA batteries, taking into account the polarity. You will have to remove the diode from the housing, which will vary depending on the drive. The laser diode is a very fragile part, so be extremely careful.
step 6 - Laser diode in a new guise!
This is what your diode should look like after being “released”.
step 7 - Preparing the AixiZ body...
Remove the sticker from the AixiZ body and unscrew the body into upper and lower parts. Inside the top there is a laser diode (5 mW), which we will replace. I used an X-Acto knife and after two light strikes, the original diode came out. In fact, such actions can damage the diode, but I have managed to avoid this before. Using a very small screwdriver, I knocked out the emitter.
step 8 - Assembling the body...
I used some hot glue and carefully installed the new DVD diode into the AixiZ case. Using pliers, I SLOWLY pressed the edges of the diode towards the body until it was flush.
step 9 - Install it in MiniMag
Once the two conductors are soldered to the positive and negative terminals of the diode, you can install the device in the MiniMag. After disassembling the MiniMag (remove the cap, reflector, lens and emitter), you will need to enlarge the MiniMag reflector using a round file or drill, or both.
step 10 - Last step
Remove the batteries from the MiniMag and after checking the polarity, carefully place the DVD laser housing on the top of the MiniMag where the emitter was previously located. Assemble the top of the MiniMag housing and attach the reflector. You won't need the plastic MiniMag lens.
Make sure the polarity of the diode is correct before you install it and connect power! You may need to shorten the wires and adjust the beam focus.
step 11 - Measure seven times
Replace the batteries (AA) and screw on the top of the MiniMag, including your new laser pointer! Attention!! Laser diodes are dangerous, so do not point the beam at people or animals.
| ]Book |
Name Author: team Format: Mixed Size: 10.31 MB Quality: Excellent Language: Russian The year of publishing: 2008 Like in a science fiction movie - you pull the trigger and the ball explodes! Learn how to make a laser like this! |
Each of us held a laser pointer in our hands. Despite the decorative use, it contains a real laser, assembled on the basis of a semiconductor diode. The same elements are installed on laser levels and.
The next popular product assembled on a semiconductor is your computer's DVD burner drive. It contains a more powerful laser diode with thermal destructive power.
This allows you to burn a layer of the disc, depositing tracks with digital information on it.
How does a semiconductor laser work?
Devices of this type are inexpensive to produce and the design is quite widespread. The principle of laser (semiconductor) diodes is based on the use of a classic p-n junction. This transition works the same as in conventional LEDs.
The difference is in the organization of radiation: LEDs emit “spontaneously”, while laser diodes emit “forced”.
The general principle of the formation of the so-called “population” quantum radiation performed without mirrors. The edges of the crystal are mechanically chipped, providing a refractive effect at the ends, akin to a mirror surface.
To obtain different types of radiation, a “homojunction” can be used, when both semiconductors are the same, or a “heterojunction”, with different materials transition.
The laser diode itself is an accessible radio component. You can buy it in stores that sell radio components, or you can extract it from an old DVD-R (DVD-RW) drive.
Important! Even the simple laser used in light pointers can cause serious damage to the retina of the eye.
More powerful installations, with a burning beam, can deprive of vision or cause burns skin. Therefore, use extreme caution when working with such devices.
With such a diode at your disposal, you can easily make a powerful laser with your own hands. In fact, the product may be completely free, or it will cost you a ridiculous amount of money.
DIY laser from a DVD drive
First, you need to get the drive itself. It can be removed from an old computer or purchased at a flea market for a nominal cost.
Information: The higher the declared recording speed, the more powerful the burning laser is used in the drive.
Having removed the case and disconnected the control cables, we dismantle the writing head along with the carriage.
To remove the laser diode:
- We connect the legs of the diode to each other using a wire (bypass). During dismantling, static electricity may accumulate and the diode may fail.
- Remove the aluminum radiator. It is quite fragile, has a mount that is structurally “tailored” for a specific DVD drive, and is not needed for further operation. Just cut the radiator with wire cutters (without damaging the diode)
- We unsolder the diode and free the legs from the shunt.
The element looks like this:
Next important element– laser power supply circuit. You won't be able to use the power supply from the DVD drive. It is integrated into the general control circuit; it is technically impossible to remove it from there. Therefore, we make the power supply circuit ourselves.
There is a temptation to just connect 5 volts with a limiting resistor and not bother with the circuit. This is the wrong approach, since any LEDs (including laser ones) are powered not by voltage, but by current. Accordingly, a current stabilizer is needed. Most affordable option– use of the LM317 chip.
The output resistor R1 is selected in accordance with the supply current of the laser diode. In this circuit, the current should correspond to 200 mA.
You can assemble a laser with your own hands in a housing from a light pointer, or you can purchase a ready-made module for a laser in electronics stores or on Chinese websites (for example, Ali Express).
The advantage of this solution is that you get a ready-made adjustable lens included. The power supply circuit (driver) easily fits into the module housing.
If you decide to make the case yourself, from some metal tube, you can use a standard lens from the same DVD drive. You just need to come up with a mounting method and the ability to adjust the focus.
Important! Focusing the beam is necessary for any design. It can be parallel (if you need range) or cone-shaped (if you need to get a concentrated thermal spot).
The lens complete with a control device is called a collimator.
To properly connect the laser from the DVD drive, you need a contact diagram. You can track the negative and positive wires by markings on the circuit board. This must be done before dismantling the diode. If this is not possible, use the standard hint:
The negative contact has an electrical connection with the diode body. Finding it won't be difficult. Regarding the minus located at the bottom, the positive contact will be on the right.
If you have a three-pin laser diode (and most do), there will be either an unused pin on the left or a photodiode connection. This happens if both the burning and reading elements are located in the same housing. 
The main body is selected based on the size of the batteries or accumulators that you plan to use. Carefully attach your homemade laser module into it, and the device is ready for use.
With the help of such a tool you can do engraving, wood burning, and cutting fusible materials (fabric, cardboard, felt, polystyrene foam, etc.).
How to make an even more powerful laser?
If you need a cutter for wood or plastic, the power of a standard diode from a DVD drive is not enough. You will either need a ready-made diode with a power of 500-800 mW, or you will have to spend a lot of time searching for suitable DVD drives. Some LG and SONY models use laser diodes with a power of 250-300 mW.
The main thing is that such technologies are available for self-production.
Step-by-step video instructions on how to make a laser from a DVD drive with your own hands
Many of you have probably heard that you can make a laser pointer or even a cutting beam at home using simple improvised means, but few people know how to make a laser yourself. Before you start working on it, be sure to familiarize yourself with the safety precautions.
Safety rules when working with laser
Improper use of the beam, especially at high power, can lead to property damage, as well as serious harm to your health or the health of bystanders. Therefore, before testing your own made copy, remember the following rules:
- Make sure there are no animals or children in the testing room.
- Never point the beam at animals or people.
- Wear safety glasses, such as welding glasses.
- Remember that even a reflected beam can damage your vision. Never shine a laser into your eyes.
- Do not use the laser to ignite objects while indoors.
The simplest laser from a computer mouse
If you need a laser just for fun, it’s enough to know how to make a laser at home from a mouse. Its power will be quite insignificant, but it will not be difficult to manufacture. All you need is a computer mouse, a small soldering iron, batteries, wires and a shutdown switch.
First, the mouse must be disassembled. It is important not to break them out, but to carefully unscrew and remove them in order. First the upper casing, followed by the lower casing. Next, using a soldering iron, you need to remove the mouse laser from the board and solder new wires to it. Now all that remains is to connect them to the shutdown switch and connect the wires to the battery contacts. Batteries can be used of any type: both finger batteries and so-called pancakes.
Thus, the simplest laser is ready.
If a weak beam is not enough for you, and you are interested in how to make a laser at home from improvised means with sufficiently high power, then you should try a more complex method of making it, using a DVD-RW drive.
To work you will need:
- DVD-RW drive (write speed must be at least 16x);
- AAA battery, 3 pcs.;
- resistor (from two to five ohms);
- collimator (can be replaced with a part from a cheap Chinese laser pointer);
- capacitors 100 pF and 100 mF;
- LED lamp made of steel;
- wires and soldering iron.
Work progress:
The first thing we need is a laser diode. It is located in the DVD-RW drive carriage. It has a larger heatsink than a regular infrared diode. But be careful, this part is very fragile. While the diode is not installed, it is best to wrap its lead with wire, since it is too sensitive to static voltage. Please pay Special attention for polarity. If the power supply is incorrect, the diode will immediately fail.
Connect the parts according to the following scheme: battery, on/off button, resistor, capacitors, laser diode. Once the functionality of the design has been verified, all that remains is to come up with a convenient housing for the laser. For these purposes, a steel body from a regular flashlight is quite suitable. Don’t forget also about the collimator, because it is the one that turns the radiation into a thin beam.
Now that you know how to make a laser at home, do not forget to follow safety precautions, store it in a special case and do not carry it with you, as law enforcement agencies may file complaints against you in this regard.
Watch the video: Laser from a DVD drive at home and with your own hands
Today we will talk about how to make a powerful green or blue laser yourself at home from scrap materials with your own hands. We will also consider drawings, diagrams and the design of homemade laser pointers with an igniting beam and a range of up to 20 km
The basis of the laser device is an optical quantum generator, which, using electrical, thermal, chemical or other energy, produces a laser beam.
Laser operation is based on the phenomenon of forced (induced) radiation. Laser radiation can be continuous, with constant power, or pulsed, reaching extremely high peak powers. The essence of the phenomenon is that an excited atom is capable of emitting a photon under the influence of another photon without its absorption, if the energy of the latter is equal to the difference in the energies of the levels of the atom before and after the radiation. In this case, the emitted photon is coherent with the photon that caused the radiation, that is, it is its exact copy. This way the light is amplified. This phenomenon differs from spontaneous radiation, in which the emitted photons have random propagation directions, polarization and phase
The probability that a random photon will cause stimulated emission from an excited atom is exactly equal to the probability of absorption of this photon by an atom in an unexcited state. Therefore, to amplify light, it is necessary that there be more excited atoms in the medium than unexcited ones. In a state of equilibrium, this condition is not satisfied, so we use various systems pumping the laser active medium (optical, electrical, chemical, etc.). In some schemes, the laser working element is used as an optical amplifier for radiation from another source.
There is no external flow of photons in a quantum generator; an inverse population is created inside it using various pump sources. Depending on the sources there are various ways pumping:
optical - powerful flash lamp;
gas discharge in the working substance (active medium);
injection (transfer) of current carriers in a semiconductor in the zone
r-n transitions;
electronic excitation (irradiation of a pure semiconductor in a vacuum with a flow of electrons);
thermal (heating of gas followed by rapid cooling;
chemical (energy use chemical reactions) and some others.
The primary source of generation is the process of spontaneous emission, therefore, to ensure the continuity of generations of photons, the existence of a positive feedback is necessary, due to which the emitted photons cause subsequent acts of induced emission. To do this, the laser active medium is placed in an optical cavity. In the simplest case, it consists of two mirrors, one of which is translucent - through it the laser beam partially exits the resonator.
Reflecting from the mirrors, the radiation beam passes repeatedly through the resonator, causing induced transitions in it. The radiation can be either continuous or pulsed. At the same time, using various devices to quickly turn the feedback off and on and thereby reduce the period of the pulses, it is possible to create conditions for generating radiation of very high power - these are the so-called giant pulses. This mode of laser operation is called Q-switched mode.
The laser beam is a coherent, monochrome, polarized, narrowly directed light flux. In a word, this is a beam of light emitted not only by synchronous sources, but also in a very narrow range, and directionally. A sort of extremely concentrated light flux.
The radiation generated by a laser is monochromatic, the probability of emission of a photon of a certain wavelength is greater than that of a closely located one, associated with the broadening of the spectral line, and the probability of induced transitions at this frequency also has a maximum. Therefore, gradually during the generation process, photons of a given wavelength will dominate over all other photons. In addition, due to the special arrangement of the mirrors, only those photons that propagate in a direction parallel to the optical axis of the resonator at a short distance from it are retained in the laser beam; the remaining photons quickly leave the resonator volume. Thus, the laser beam has a very small divergence angle. Finally, the laser beam has a strictly defined polarization. To do this, various polarizers are introduced into the resonator; for example, they can be flat glass plates installed at a Brewster angle to the direction of propagation of the laser beam.
The working wavelength of the laser, as well as other properties, depend on what working fluid is used in the laser. The working fluid is “pumped” with energy to obtain the effect of electron population inversion, which causes stimulated emission of photons and an optical amplification effect. The simplest form The optical resonator consists of two parallel mirrors (there can also be four or more of them) located around the laser working fluid. The stimulated radiation of the working fluid is reflected back by the mirrors and is again amplified. Until the moment it comes out, the wave can be reflected many times.
So, let us briefly formulate the conditions necessary to create a source of coherent light:
you need a working substance with inverted population. Only then can light amplification be achieved through forced transitions;
the working substance should be placed between the mirrors that provide feedback;
the gain given by the working substance, which means the number of excited atoms or molecules in the working substance must be greater than a threshold value depending on the reflection coefficient of the output mirror.
The following types of working fluids can be used in the design of lasers:
Liquid. It is used as a working fluid, for example, in dye lasers. The composition includes an organic solvent (methanol, ethanol or ethylene glycol) in which chemical dyes (coumarin or rhodamine) are dissolved. The operating wavelength of liquid lasers is determined by the configuration of the dye molecules used.
Gases. In particular, carbon dioxide, argon, krypton or gas mixtures, as in helium-neon lasers. “Pumping” with the energy of these lasers is most often carried out using electrical discharges.
Solids (crystals and glasses). The solid material of such working fluids is activated (doped) by adding a small amount of chromium, neodymium, erbium or titanium ions. Common crystals used are yttrium aluminum garnet, lithium yttrium fluoride, sapphire (aluminum oxide), and silicate glass. Solid-state lasers are usually "pumped" by a flash lamp or other laser.
Semiconductors. A material in which the transition of electrons between energy levels can be accompanied by radiation. Semiconductor lasers are very compact and "pumped" by electrical current, allowing them to be used in consumer devices such as CD players.
To turn an amplifier into an oscillator, it is necessary to organize feedback. In lasers, this is achieved by placing the active substance between reflecting surfaces (mirrors), forming a so-called “open resonator” due to the fact that part of the energy emitted by the active substance is reflected from the mirrors and again returns to the active substance
The laser uses optical resonators various types- with flat mirrors, spherical, combinations of flat and spherical, etc. In optical resonators that provide feedback in the Laser, only certain specific types of oscillations of the electromagnetic field can be excited, which are called natural oscillations or modes of the resonator.
Modes are characterized by frequency and shape, i.e., the spatial distribution of vibrations. In a resonator with flat mirrors, the types of oscillations corresponding to plane waves propagating along the axis of the resonator are predominantly excited. A system of two parallel mirrors resonates only at certain frequencies - and in the laser also plays the role that an oscillatory circuit plays in conventional low-frequency generators.
The use of an open resonator (and not a closed one - a closed metal cavity - characteristic of the microwave range) is fundamental, since in the optical range a resonator with dimensions L = ? (L is the characteristic size of the resonator, ? is the wavelength) simply cannot be manufactured, and at L >> ? a closed resonator loses its resonant properties because the number of possible types of oscillations becomes so large that they overlap.
The absence of side walls significantly reduces the number of possible types of oscillations (modes) due to the fact that waves propagating at an angle to the axis of the resonator quickly go beyond its limits, and allows maintaining the resonant properties of the resonator at L >> ?. However, the resonator in the laser not only provides feedback by returning radiation reflected from the mirrors to the active substance, but also determines the spectrum of the laser radiation, its energy characteristics, and the direction of the radiation.
In the simplest approximation of a plane wave, the condition for resonance in a resonator with flat mirrors is that an integer number of half-waves fits along the length of the resonator: L=q(?/2) (q is an integer), which leads to an expression for the frequency of the oscillation type with the index q: ?q=q(C/2L). As a result, the radiation spectrum of light, as a rule, is a set of narrow spectral lines, the intervals between which are identical and equal to c/2L. The number of lines (components) for a given length L depends on the properties of the active medium, i.e., on the spectrum of spontaneous emission at the quantum transition used and can reach several tens and hundreds. Under certain conditions, it turns out to be possible to isolate one spectral component, i.e., to implement a single-mode lasing regime. The spectral width of each component is determined by the energy losses in the resonator and, first of all, by the transmission and absorption of light by the mirrors.
The frequency profile of the gain in the working substance (it is determined by the width and shape of the line of the working substance) and the set of natural frequencies of the open resonator. For open resonators with a high quality factor used in lasers, the resonator passband ??p, which determines the width of the resonance curves of individual modes, and even the distance between neighboring modes ??h turn out to be less than the gain linewidth ??h, and even in gas lasers, where the line broadening is the smallest. Therefore, several types of resonator oscillations enter the amplification circuit.
Thus, the laser does not necessarily generate at one frequency; more often, on the contrary, generation occurs simultaneously at several types of oscillations, for which the amplification? more losses in the resonator. In order for the laser to operate at one frequency (in single-frequency mode), it is necessary, as a rule, to take special measures (for example, increase losses, as shown in Figure 3) or change the distance between the mirrors so that only one gets into the gain circuit. fashion. Since in optics, as noted above, ?h > ?p and the generation frequency in a laser is determined mainly by the resonator frequency, then in order to keep the generation frequency stable, it is necessary to stabilize the resonator. So, if the gain in the working substance covers the losses in the resonator for certain types of oscillations, generation occurs on them. The seed for its occurrence is, as in any generator, noise, which represents spontaneous emission in lasers.
In order for the active medium to emit coherent monochromatic light, it is necessary to introduce feedback, i.e., part of the light flux emitted by this medium is directed back into the medium to produce stimulated emission. Positive Feedback is carried out using optical resonators, which in the elementary version are two coaxially (parallel and along the same axis) mirrors, one of which is translucent, and the other is “deaf,” i.e., completely reflects the light flux. The working substance (active medium), in which an inverse population is created, is placed between the mirrors. Stimulated radiation passes through the active medium, is amplified, reflected from the mirror, passes through the medium again and is further amplified. Through a translucent mirror, part of the radiation is emitted into the external environment, and part is reflected back into the environment and amplified again. Under certain conditions, the flux of photons inside the working substance will begin to increase like an avalanche, and the generation of monochromatic coherent light will begin.
The principle of operation of an optical resonator, the predominant number of particles of the working substance, represented by open circles, are in the ground state, i.e., at the lower energy level. Only a small number of particles, represented by dark circles, are in an electronically excited state. When the working substance is exposed to a pumping source, the majority of particles go into an excited state (the number of dark circles has increased), and an inverse population is created. Next (Fig. 2c) spontaneous emission of some particles occurring in an electronically excited state occurs. Radiation directed at an angle to the axis of the resonator will leave the working substance and the resonator. Radiation, which is directed along the axis of the resonator, will approach the mirror surface.
For a translucent mirror, part of the radiation will pass through it into environment, and part of it will be reflected and again directed into the working substance, involving particles in an excited state in the process of stimulated emission.
At the “deaf” mirror, the entire radiation flux will be reflected and again pass through the working substance, inducing radiation from all remaining excited particles, which reflects the situation when all the excited particles gave up their stored energy, and at the output of the resonator, on the side of the translucent mirror, a powerful flux of induced radiation was formed.
Basic structural elements lasers include a working substance with certain energy levels of their constituent atoms and molecules, a pump source that creates an inverse population in the working substance, and an optical resonator. There are a large number of different lasers, but they all have the same and simple schematic diagram device, which is shown in Fig. 3.
The exception is semiconductor lasers due to their specificity, since everything about them is special: the physics of the processes, pumping methods, and design. Semiconductors are crystalline formations. In an individual atom, the electron energy takes on strictly defined discrete values, and therefore the energy states of the electron in the atom are described in the language of levels. In a semiconductor crystal, energy levels form energy bands. In a pure semiconductor that does not contain any impurities, there are two bands: the so-called valence band and the conduction band located above it (on the energy scale).
Between them there is a gap of forbidden energy values, which is called the bandgap. At a semiconductor temperature equal to absolute zero, the valence band should be completely filled with electrons, and the conduction band should be empty. In real conditions, the temperature is always above absolute zero. But an increase in temperature leads to thermal excitation of electrons, some of them jump from the valence band to the conduction band.
As a result of this process, a certain (relatively small) number of electrons appears in the conduction band, and a corresponding number of electrons will be missing in the valence band until it is completely filled. An electron vacancy in the valence band is represented by a positively charged particle, which is called a hole. The quantum transition of an electron through the band gap from bottom to top is considered as a process of generating an electron-hole pair, with electrons concentrated at the lower edge of the conduction band, and holes at the upper edge of the valence band. Transitions through the forbidden zone are possible not only from bottom to top, but also from top to bottom. This process is called electron-hole recombination.
When a pure semiconductor is irradiated with light whose photon energy slightly exceeds the band gap, three types of interaction of light with matter can occur in the semiconductor crystal: absorption, spontaneous emission and stimulated emission of light. The first type of interaction is possible when a photon is absorbed by an electron located near the upper edge of the valence band. In this case, the energy power of the electron will become sufficient to overcome the band gap, and it will make a quantum transition to the conduction band. Spontaneous emission of light is possible when an electron spontaneously returns from the conduction band to the valence band with the emission of an energy quantum - a photon. External radiation can initiate the transition to the valence band of an electron located near the lower edge of the conduction band. The result of this third type of interaction of light with the semiconductor substance will be the birth of a secondary photon, identical in its parameters and direction of movement to the photon that initiated the transition.
To generate laser radiation, it is necessary to create an inverse population of “working levels” in the semiconductor - to create a sufficiently high concentration of electrons at the lower edge of the conduction band and a correspondingly high concentration of holes at the edge of the valence band. For these purposes, pure semiconductor lasers are usually pumped by an electron flow.
The resonator mirrors are polished edges of the semiconductor crystal. The disadvantage of such lasers is that many semiconductor materials generate laser radiation only at very high low temperatures, and the bombardment of semiconductor crystals by a stream of electrons causes it to heat up greatly. This requires additional cooling devices, which complicates the design of the device and increases its dimensions.
The properties of semiconductors with impurities differ significantly from the properties of unimpurity, pure semiconductors. This is due to the fact that atoms of some impurities easily donate one of their electrons to the conduction band. These impurities are called donor impurities, and a semiconductor with such impurities is called an n-semiconductor. Atoms of other impurities, on the contrary, capture one electron from the valence band, and such impurities are acceptor, and a semiconductor with such impurities is a p-semiconductor. The energy level of impurity atoms is located inside the band gap: for n-semiconductors - near the lower edge of the conduction band, for /-semiconductors - near the upper edge of the valence band.
If an electric voltage is created in this area so that there is a positive pole on the side of the p-semiconductor, and a negative pole on the side of the p-semiconductor, then under the influence electric field electrons from the n-semiconductor and holes from the n-semiconductor will move (inject) into the region of the p-n junction.
When electrons and holes recombine, photons will be emitted, and in the presence of an optical resonator, laser radiation can be generated.
The mirrors of the optical resonator are polished edges of the semiconductor crystal, oriented perpendicularly p-n plane- transition. Such lasers are miniature, since the size of the semiconductor active element can be about 1 mm.
Depending on the characteristic under consideration, all lasers are divided as follows).
First sign. It is customary to distinguish between laser amplifiers and generators. In amplifiers, weak laser radiation is supplied at the input, and it is correspondingly amplified at the output. There is no external radiation in the generators; it arises in the working substance due to its excitation using various pump sources. All medical laser devices are generators.
The second sign is physical state working substance. In accordance with this, lasers are divided into solid-state (ruby, sapphire, etc.), gas (helium-neon, helium-cadmium, argon, carbon dioxide, etc.), liquid (liquid dielectric with impurity working atoms of rare earth metals) and semiconductor (arsenide -gallium, gallium arsenide phosphide, lead selenide, etc.).
The method of exciting the working substance is the third distinctive feature of lasers. Depending on the excitation source, lasers are distinguished: optically pumped, pumped by a gas discharge, electronic excitation, injection of charge carriers, thermally pumped, chemically pumped, and some others.
The laser emission spectrum is the next classification feature. If the radiation is concentrated in a narrow range of wavelengths, then the laser is considered monochromatic and its technical data indicates a specific wavelength; if in a wide range, then the laser should be considered broadband and the wavelength range is indicated.
Based on the nature of the emitted energy, pulsed lasers and lasers with continuous radiation are distinguished. The concepts of a pulsed laser and a laser with frequency modulation of continuous radiation should not be confused, since in the second case we essentially receive intermittent radiation of various frequencies. Pulsed lasers have high power in a single pulse, reaching 10 W, while their average pulse power, determined by the corresponding formulas, is relatively small. For continuous frequency modulated lasers, the power in the so-called pulse is lower than the power of continuous radiation.
Based on the average radiation output power (the next classification feature), lasers are divided into:
· high-energy (generated flux density, radiation power on the surface of an object or biological object - over 10 W/cm2);
· medium-energy (generated radiation power flux density - from 0.4 to 10 W/cm2);
· low-energy (the generated radiation power flux density is less than 0.4 W/cm2).
· soft (generated energy irradiation - E or power flux density on the irradiated surface - up to 4 mW/cm2);
· average (E - from 4 to 30 mW/cm2);
· hard (E - more than 30 mW/cm2).
In accordance with the “Sanitary norms and rules for the design and operation of lasers No. 5804-91,” lasers are divided into four classes according to the degree of danger of the generated radiation for operating personnel.
First class lasers include: technical devices, the output collimated (enclosed in a limited solid angle) radiation of which does not pose a danger when irradiating human eyes and skin.
Second class lasers are devices whose output radiation poses a danger when irradiating the eyes with direct and specularly reflected radiation.
Lasers of the third class are devices whose output radiation poses a danger when irradiating the eyes with direct and specularly reflected, as well as diffusely reflected radiation at a distance of 10 cm from a diffusely reflective surface, and (or) when irradiating the skin with direct and specularly reflected radiation.
Fourth class lasers are devices whose output radiation poses a hazard when the skin is irradiated with diffusely reflected radiation at a distance of 10 cm from a diffusely reflective surface.
Who in childhood did not dream of laser? Some men still dream. Conventional laser pointers with low power are no longer relevant for a long time, since their power leaves much to be desired. There are 2 options left: buy an expensive laser or make it at home using improvised materials.
- From an old or broken DVD drive
- From a computer mouse and flashlight
- From a kit of parts purchased at an electronics store
How to make a laser at home from an old oneDVDdrive
- Find a non-working or unwanted DVD drive that has a recording speed greater than 16x and outputs more than 160mW of power. Why can't you take a recordable CD, you ask? The fact is that its diode emits infrared light, invisible to the human eye.
- Remove the laser head from the drive. To access the “internals”, unscrew the screws located on the bottom of the drive and remove the laser head, which is also held in place by screws. It may be in a shell or under a transparent window, or maybe even outside. The most difficult thing is to remove the diode itself from it. Caution: The diode is very sensitive to static electricity.
- Get a lens, without which it will be impossible to use the diode. You can use a regular magnifying glass, but then you will have to twist and adjust it every time. Or you can purchase another diode included with the lens, and then replace it with the diode removed from the drive.
- Next you will have to buy or assemble a circuit to power the diode and assemble the structure together. In a DVD drive diode, the center pin acts as the negative terminal.
- Connect a suitable power source and focus the lens. All that remains is to find a suitable container for the laser. You can use a metal flashlight of suitable size for these purposes.
- We recommend watching this video, where everything is shown in great detail:
How to make a laser from a computer mouse
The power of a laser made from computer mouse will be much less than the laser power produced by the previous method. The manufacturing procedure is not very different.
- First, find an old or unnecessary mouse with visible laser any color. Mice with an invisible glow are not suitable for obvious reasons.
- Next, carefully disassemble it. Inside you will notice a laser that will have to be soldered using a soldering iron.
- Now repeat steps 3-5 from the instructions above. The difference between such lasers, we repeat, is only in power.
Metal cutting with laser is the most advanced and modern technology, but also the most expensive. Its main advantage is the beam, with unlimited possibilities. Do-it-yourself laser cutting of metal makes it possible to cut workpieces in any direction, while the cut edges will be neat and do not require further processing. In addition, the laser beam is monochrome, that is, it has a clear and strict wavelength (it is fixed) and a constant frequency. This makes it easy to focus even with ordinary lenses.
So, equipment for laser cutting of metal is a thing that is inaccessible to many; it is too expensive. Therefore, home craftsmen get out of the situation by using various almost unnecessary items from which they make homemade device. There are many options for making laser cutters with your own hands, one of them is based on the use of a laser pointer, which will be discussed.
Making a homemade laser cutter
To assemble the cutter you will need:
- laser pointer;
- flashlight;
- CD/DVD-RW – not necessarily new, the main thing is that it has a working laser with a drive;
- tools: soldering iron and screwdrivers.
Please note that a DVD writer is required to assemble the laser cutting machine. You need to disassemble it and find a carriage with a laser that writes and reads information from the compact disk. There should be a red diode next to the carriage. It also needs to be removed with a soldering iron, because it is soldered to the circuit in the plateau. By the way, the diode must be handled carefully; you cannot shake it, drop it, hit it, etc.
Now here's the moment - laser cutter(aka diode) consumes more current than a laser line diode. Therefore, care must be taken to ensure that there is more of this current. There are several options here, but since a flashlight was prepared, its batteries will be used to power the diode. The laser pointer has a smaller battery and only one battery.
Now you can proceed to assembling the laser cutter.
- The laser pointer is disassembled.
- Its diode is removed from it, and a diode removed from the DVD is installed in its place.
- Now you need to connect to a new, more powerful power source. To do this, the front part of the pointer is installed in the flashlight, having first removed the lens from it. It is secured to the device using a clamping nut screwed onto the thread.
- The diode is connected by wires from the terminals that connect to the batteries. It is important here not to confuse the polarity of the connection.
- Basically, everything is ready. A miniature laser cutter can be used.
Of course, they won’t be able to cut metal, but paper and polymer films will be burned through. Even matches can be lit with this device.
Laser for cutting metal
By adding several devices to those used above, you can make a more powerful device, almost 500 times more powerful. Added:
- an optical collimator is a device that creates a light flux from parallel beams;
- capacitors 100pF and 100mF;
- one resistor with a resistance of 2-5 Ohms.
A driver is assembled from radio components together with a diode, which will output the cutter to the required power. The optical collimator has a place where you can install a diode, and this is its great advantage. That is, instead of a laser pointer, this installation uses a collimator. In addition, the pointer is made of plastic, and during the cutting process its body will become very hot. This will lead to its warping, and the installation itself will not cool well.
All other assembly technology is exactly the same as in the previous case. It should be noted that the diode is a very sensitive element, so it is necessary to remove static electricity from it before use. This can be done using an antistatic wrist strap. If you don’t have a bracelet, you can wind a thin wire around the diode, which will remove static from the part.
Making a laser with your own hands for cutting metal requires certain actions that affect its quality functionality. First of all, you need to test the assembled driver. To do this, you will have to find another exactly the same diode. It is connected to the device and tested with a multimeter. 300-350 mA is the norm for many homemade devices. But if there is a need to increase the power of the entire unit, then it is better if the multimeter shows 500 mA. True, for such a cutter you will have to assemble another driver that supports this current value.
Let's not forget about the aesthetic side of the issue. You can come up with different housing options. For example, a small LED flashlight. It is recommended to store the finished device in a special case so that the optical collimator lens does not become covered with dust. By the way, such a cutter may cause law enforcement there are a lot of questions, so you shouldn’t carry it around in your pocket.
It should be noted that the diode power depends on the current, not the voltage. When the latter increases, the standard brightness of the diode is exceeded, and this leads to destruction of the resonator in the diode design. That is, the light source stops heating, which is necessary for a laser cutter. It just glows like a regular light bulb. Temperatures also affect the performance of the diode. At low temperatures its performance increases; at high temperatures the resonator fails.
Of course, there is no need to say that this laser cutter will cut thick workpieces at home. But it will cut thin sheet metal or aluminum foil accurately. Such settings will be useful to designers who from various unnecessary items make different designer accessories. For example, you can make an unusual lamp from an aluminum beer can.
When in the household there is a need to cut a metal sheet, then you can’t do without a laser cutter, assembled with your own hands.
Second life for simple things
A home craftsman will always find a use even for things that have become unusable. So, an old laser pointer can find a second life and turn into a laser cutter. In order to bring this idea to life, you will need:
- Laser pointer.
- Flashlight.
- Batteries (it is better to take rechargeable ones).
- CD/DVD-RW recorder with a drive with a working laser.
- Soldering iron.
- Screwdrivers included.
Work begins by removing the laser cutter from the drive. This painstaking work requiring maximum attention. When removing the top fastener, you may come across a carriage with a built-in laser. It can move in two directions. The carriage must be removed with extreme care and all detachable devices and screws must be removed carefully. Next, you need to remove the red diode that performs the burning. This work can be done using a soldering iron. It should be noted that this important detail requires increased attention. It is not recommended to shake or drop it.
To increase the power of the laser cutter in the prepared pointer, it is necessary to replace the “native” diode with the one removed from the recorder.
The pointer should be disassembled sequentially and carefully. It unwinds and splits into pieces. The part that requires replacement is located at the top. If it is difficult to remove it, then you can help yourself with a knife, slightly shaking the pointer. A new one is installed in place of the original diode. You can secure it with glue.
The next stage of work is the construction of a new building. This is where an old flashlight comes in handy. Thanks to it, the new laser will be convenient to use and connect to power. The improved end part of the pointer is installed in the flashlight body. Then power is connected from the batteries to the diode. When connecting, it is very important to set the polarity correctly. Before assembling the flashlight, you need to remove the glass and the remaining parts of the pointer so that nothing interferes with the direct path of the laser beam.
Before using the assembled unit with your own hands, you need to once again check whether the laser is firmly fixed and level, and whether the polarity of the wires is connected correctly.
If everything is done correctly, the unit can be used. It will be difficult to work on metal, since the device has little power, but it is quite possible to burn through paper, polyethylene or something similar.
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Improved model
A more powerful homemade laser cutter can be made. To work you need to prepare:
- CD/DVD-RW recorder (non-working model can be used).
- Resistors 2-5 Ohm.
- Batteries.
- Capacitors 100 pF and 100 mF.
- The wire.
- Soldering iron.
- Collimator.
- LED flashlight in a steel housing.
A driver is assembled from these components, which will provide the required power to the cutter through the board. It should be remembered that the current source is not directly connected to the diode. Otherwise it will become completely unusable. Power can only be connected through a ballast resistor.
The body with the lens acts as a collimator. It is she who will collect the rays into a single beam. This part can be purchased at a specialty store. The good part is that it has a socket for mounting a laser diode.
This laser is manufactured in the same way as the previous model. During work, it is necessary to use antistatic wristbands to remove static voltage from the laser diode. If it is not possible to purchase such bracelets, a thin wire can be used and wound around a diode. Then you can proceed to assembling the driver.
Making a powerful burning laser with your own hands is not a difficult task, however, in addition to the ability to use a soldering iron, you will need to be attentive and careful in your approach. It’s worth noting right away that deep knowledge from the field of electrical engineering is not needed here, and you can make a device even at home. The main thing when working is to take precautions, since exposure to a laser beam is harmful to the eyes and skin.
A laser is a dangerous toy that can cause harm to health if used carelessly. Do not point the laser at people or animals!
What will you need?
Any laser can be divided into several components:
- light flux emitter;
- optics;
- power supply;
- current supply stabilizer (driver).
To make a powerful homemade laser, you will need to consider all these components separately. The most practical and easiest to assemble is a laser based on a laser diode, which we will consider in this article.
Where can I get a diode for a laser?
The working element of any laser is a laser diode. You can buy it at almost any radio store, or get it from a non-working CD drive. The fact is that drive inoperability is rarely associated with failure of the laser diode. If you have a broken drive, you can extra costs get the required element. But you need to take into account that its type and properties depend on the modification of the drive.
The weakest laser operating in the infrared range is installed in CD-ROM drives. Its power is only enough to read CDs, and the beam is almost invisible and is not capable of burning objects. The CD-RW has a built-in more powerful laser diode, suitable for burning and designed for the same wavelength. It is considered the most dangerous, as it emits a beam in a zone of the spectrum invisible to the eye.
The DVD-ROM drive is equipped with two weak laser diodes, the energy of which is only sufficient for reading CDs and DVD discs. The DVD-RW burner contains a high-power red laser. Its beam is visible in any light and can easily ignite certain objects.
The BD-ROM contains a violet or blue laser, which is similar in parameters to the analogue from the DVD-ROM. From BD-RE recorders you can get the most powerful laser diode with a beautiful violet or blue beam capable of burning. However, finding such a drive for disassembly is quite difficult, and a working device is expensive.
The most suitable one is a laser diode taken from a DVD-RW drive. The highest quality laser diodes are installed in LG, Sony and Samsung drives.
The higher the DVD drive's writing speed, the more powerful the laser diode installed in it.
Drive disassembly
Having the drive in front of you, first remove the top cover by unscrewing 4 screws. Then remove the movable mechanism, which is located in the center and connected to printed circuit board flexible cable. The next goal is a laser diode, securely pressed into a radiator made of aluminum or duralumin alloy. It is recommended to provide protection against static electricity before dismantling it. To do this, the leads of the laser diode are soldered or wrapped with thin copper wire.
Next, there are two possible options. The first involves operating a finished laser in the form of a stationary installation together with a standard radiator. The second option is to assemble the device in the body of a portable flashlight or laser pointer. In this case, you will have to apply force to cut through or saw the radiator without damaging the radiating element.
Driver
Laser power supply must be handled responsibly. As with LEDs, it must be a stabilized current source. On the Internet there are many circuits powered by a battery or accumulator through a limiting resistor. The sufficiency of this solution is questionable, since the voltage on the battery or battery changes depending on the charge level. Accordingly, the current flowing through the laser emitting diode will deviate greatly from the nominal value. As a result, the device will not work efficiently at low currents, and at high currents it will lead to a rapid decrease in the intensity of its radiation.
The best option is to use a simple current stabilizer built on the basis. This microcircuit belongs to the category of universal integrated stabilizers with the ability to independently set the output current and voltage. The microcircuit operates in a wide range of input voltages: from 3 to 40 volts.
An analogue of LM317 is the domestic chip KR142EN12.
For the first laboratory experiment, the diagram below is suitable. The only resistor in the circuit is calculated using the formula: R=I/1.25, where I is the rated laser current (reference value).
Sometimes a polar capacitor of 2200 μFx16 V and a non-polar capacitor of 0.1 μF are installed at the output of the stabilizer in parallel with the diode. Their participation is justified in the case of supplying voltage to the input from a stationary power supply, which can miss an insignificant alternating component and impulse noise. One of these circuits, powered by a Krona battery or a small battery, is presented below. 
The diagram shows the approximate value of resistor R1. To accurately calculate it, you must use the above formula.
Having collected electrical diagram, you can make a preliminary switching on and, as proof of the circuit’s operability, observe the bright red scattered light of the emitting diode. Having measured its actual current and body temperature, it is worth thinking about the need to install a radiator. If the laser will be used in a stationary installation at high currents for a long time, then passive cooling must be provided. Now there is very little left to achieve the goal: focus and get a narrow beam of high power.
Optics
In scientific terms, it's time to build a simple collimator, a device for producing beams of parallel light rays. Ideal option For this purpose there will be a standard lens taken from the drive. With its help you can obtain a fairly thin laser beam with a diameter of about 1 mm. The amount of energy of such a beam is enough to burn through paper, fabric and cardboard in a matter of seconds, melt plastic and burn through wood. If you focus a thinner beam, this laser can cut plywood and plexiglass. But setting up and securely attaching the lens to the drive is quite difficult due to its small focal length.
It is much easier to build a collimator based on a laser pointer. In addition, its case can accommodate a driver and a small battery. The output will be a beam with a diameter of about 1.5 mm and a smaller burning effect. In foggy weather or heavy snowfall, you can observe incredible light effects by directing the light stream into the sky.
Through the online store you can purchase a ready-made collimator, specifically designed for mounting and tuning a laser. Its body will serve as a radiator. Knowing the sizes of everyone components device, you can buy a cheap LED flashlight and use its housing.
In conclusion, I would like to add a few phrases about the dangers of laser radiation. First, never point the laser beam into the eyes of people or animals. This leads to serious visual impairment. Secondly, wear green glasses when experimenting with the red laser. They block most of the red portion of the spectrum from passing through. The amount of light transmitted through the glasses depends on the wavelength of the radiation. Look from the side at the laser beam without protective equipment allowed only for a short time. Otherwise, eye pain may occur.
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